Dehydrating apparatus



1950 D. B. VINCENT 2,518,582

DEHYDRATING APPARATUS Filed Oct. 21, 1946 3 Sheets-Sheet 1 Aug. 15, 1950D. B. VINCENT DEHYDRATING APPARATUS 3 Sheets-Sheet 2 Filed Oct. 21; 1946W M w 15, 1950 D. WNCENT DEHYDRATING APPARATUS s Sheets-Sheet 3 FiledOct. 21, 1946 WT MN Patented Aug. 15, 1950 UNITED STATES PATENT OFFICEDEHYDRATING APPARATUS Daniel B. Vincent, Tampa, Fla.

Application October 21, 1946, Serial No. 704,689

16 Claims.

The present invention relates to dehydrating apparatus and aimsgenerally to improve existing dehydrators to more accurately andeconomically control the dehydration of moistureladen commodities to adesired content.

One of the primary objects of the invention is the provision of animproved apparatus wherein the material to be dehydrated ispneumatically conveyed in a plurality of directions by a current ofheated products of combustion and drying air and in which thetemperature and volume of the products of combustion and drying air arecontrolled according to the unspent drying gases before dehydration iscompleted.

More specifically, the invention aims to provide an improved apparatusfor dehydration of forage and like agricultural products in which thefinal drying step may be variably controlled by the addition of gases ofhigher or lower temperature according to an intermediate condition ofthe drying operation so that the material may be more uniformly andaccurately dehydrated to a predetermined moisture content than hasheretofore been possible.

The apparatus is particularly adaptable to the uniform dehydration ofshredded citrus waste material processed to produce a stock feedaccording to my Patent No. 2,215,944, which material should bedehydrated to a moisture content of approximately percentto'prevent'spoilage.

Previously, in dehydrating such citrus cannery waste material, thematerial has been shredded and passed through either open-ended drumdryers or through a three-pass conventional type dryer which is sealedat both ends except for the entering and discharge ports. In both ofthese prior types of dehydration apparatuses no provision is made todetermine the quality or moisture content condition of the materialuntil it passes from the exhaust or discharge end. Since citrus cannerywaste is widely variable in moisture content and adaptability todehydration, dehydrators have produced a considerable quantity of moistmaterial as well as over-dried material.

One triple-pass dehydrating apparatus, above referred to, is illustratedand described in the U. S. patent to Gerald D. Arnold No. 1,988,677 ofJanuary 22, 1935. Such triple-pass dryer is preferable to the open-endeddrying drum but the change in temperature of the drying gases passingthrough the machine is indicated and controlled by the temperature ofthe gases and fuel which have already passed through the dryer. Hence,the subsequent regulation of furnace gases, based on finished material,may lead to 2 trouble or undesirable results on other feed than in theintermediate stage of dehydration within the dryer due to thepossibility of difierent moisture content or adaptability todehydration.

The present invention provides apparatus suitable for rapidly anduniformly dehydrating citrus cannery waste and like material which mayvary widely as to moisture content as well as adaptability todehydration.

The above and other aims and objects of the invention will be apparentto persons skilled in the art from a consideration of the accompanyingdrawings and annexed description illustrating and describing two formsof apparatus embodying the invention.

' In the drawings Fig. 1 is a side elevation of a dehydratinginstallation suitable for the dehydration of shredded citrus waste stockfeed, parts of the apparatus being broken away and shown in section soas better to illustrate the construction;

Fig. 2 is a transverse sectional elevation taken on the line 22 of Fig.l;

Fig. 3 is an enlarged detail central sectional view of the dehydratorshown in Fig. 1;

Fig. 4 is a diagrammatic view of one suitable system of control;

Fig. 5 is an enlarged fragmental sectional view of one end of adehydrator drum unit according to an alternative form of apparatus; and

Fig. 6 is an end elevation of the drum unit shown in Fig. 5 as taken onthe line 66 of Fig. 5.

. The material to be dehydrated is preferably shredded or comminuted tosuch size and fineness as to be capable of being, at least momentarily,suspended in a pneumatic current established through the dehydratingchamber. In the case of citrus waste stock feed, shredding orcomminution of the orange or grapefruit half sections, as they arereceived from the canneries, is desirable as it permits of chemicaltreatment and mechanical pressing or dewatering of a substantialquantity of water from the material, thus reducing the moisture contentthereof to approximately to percent as taught in my Patent No.2,215,944, aforesaid. Such comminuted material necessarily comprises asubstantial portion of fines, which are more readily dehydrated than thelarger pieces and hence are watering, as referred to above, will varywidely as to moisture content. Hence, the material is variable as toinitial moisture content and as to size or adaptability to dehydration.

Broadly, the apparatus of the invention comprises means for establishinga current of heated gas of sub-atmospheric pressure to suspend and movematerial variable in moisture content and adaptability to dehydration,and means for variably controlling the dehydration of the material at anintermediate stage of dehydration in accordance with the temperature ofthe material and gases at said intermediate stage of dehydration.Preferably, the material is passed through successive irmer,intermediate and outer dehydration chambers or drums and the temperatureof the gases and the rate of dehydration is variably controlled, as byadmitting previously unused heated gases or cooling air to the outerdrying chamber, varying the volume of the products of combustion inaccordance with the temperature of the gases and material emerging froman intermediate dehydrating chamber, varying the frequency at which thematerial is tumbled in the current, and optionally varying the velocityof the current.

According to the invention, the method may be practiced by suitableapparatus comprising a furnace I of conventional construction fired bysuitable means subject to variable control, as for example, a fuel oilburner 2 suppiled with fuel oil through pipe 3 and discharging itsproducts of combustion in the furnace I. The rate of flow of oil throughpipe 3 to the burner 2 may be controlled by valve 5 which in turn iscontrolled by a pressure diaphragm control device 4 supplied with airunder pressure by line '6, the pressure in which may be regulated by aswitch connected to a source of air under pressure M. The intermediatecontrol devices connecting the air lines 6 and M comprise a controlvalve I and a controlling thermostat l I, therefor, which thermostat isadapted to be positioned within the drying chamber at a selectedintermediate zone of dehydration. I

The control valves and thermostat may be of any of the well known typesin the art and preferably are arranged to vary the amount of fuel oilflowing to the burner 2 in accordance with temperature requirementsaffecting the thermostat II. Thus, as the temperature surrounding thethermostat falls and there is a requirement for more heat, an additionalvolume of fuel is supplied to the burner 2 resulting in an increase inthe volume of products of combustion within the furnace to be suppliedto the dehydration apparatus.

The products of combustion of the furnace I are delivered through a hotair duct l2 leading to the inlet end of a dehydrating chamber and thematerial to be dehydrated may be fed to the hot air duct [2 by aspillway or chute I3 supplied by a feeding hopper I4 and air lock l5 asis usual in the art.

The material is discharged from the dehydrating chamber tln'ough adischarge outlet I! leading to a collector l8 having a. discharge outletl9 at the lower end thereof. The collector is supplied with suction bymeans of a fan 20 driven by a motor 2| and connected to duct 22 so as tocreate a material-conveying current of sub-atmospheric pressure throughthe dehydrating chamber. The dehydrated material passing through thedischarge outlet 19 of the collector I8 is conveyed cessive drumsproviding correspondingly reduced velocities as established by thesuction fan. The forms of drying chambers may vary considerably inconstruction as shown in the annexed drawings.

Referring to Figs. 1 to 3 inclusive, the dehydrating chamber preferablycomprises a stationary casing 30 having end walls 3| and 32. R0- tatablymounted within the casing 30 are a series of concentric drums, hereinillustrated as comprising an inner drum 33, an intermediate drum 34 andan outer drum 35. The inner drum 33 comprises a tubular casing havingend portions extending through the end walls 3| and 32 and having aninlet end 36 surrounding or aligned with the discharge end of the hotair duct 12 as is clearly shown in Fig. 3. The inner faces of the drums33, 34 and 35 may be provided with inwardly extending radially disposedpaddles or shelves 33 34 and 35 adapted to repeatedly tumble thematerial to be dried by repeatedly lifting and dropping it across thecurrent of hot drying gases as is customary in the art.

The inlet end 36 of the inner drum 33 rotates relative to the stationaryhot air duct [2 and a rotary bearing support therefor may be provided byan elongated sleeve 31 surrounding and spaced from the drum 33, theportion of the sleeve 3'! exteriorly of the casing 30 being providedwith an annular tire 38 supported in driving rollers 39 by means ofwhich the drum is rotated. The end of the sleeve 37 is provided with aplurality of air inlets 40 and the opposite end, within the drum, isprovided with air outlets 4|. Accordingly, a current of air isestablished between inlet end 36 of the inner drum 33 and the sleeveWhich maintains the bearing sleeve 3'! much cooler than the inlet end 36of the drum 33. The current of air is discharged into the dehydratingchamber, preferably in the intermediate drying stage, but it is heatedby contact with the inlet end 36 of drum 33 to substantially thetemperature of gas in the intermediate drying chamber and hence is notdetrimental to the dehydrating action therein.

The intermediate drum 34 may be an imperforate' cylindrical shellsurrounding the inner drum 33 and spaced therefrom by supporting members34 The drum 34 is preferably of less length than the drum 33 and has anopen end 42 and a closed end 42 opposite the inlet 36. The inner drum 33is preferably provided with an end wall or partition 43 and a series ofoutlet openlngs 44 providing a passage between the inner drum andintermediate drum 34 for the material being dehydrated.

The open end 42 of the intermediate drum is preferably spaced from theend wall 3| of the casing 30 providing an annular control chamber 0 inwhich the controlling regulator or thermostat H is positioned, andthrough which the partially dehydrated material must pass in itstraverse to the final dehydrating chamber or drum.

The outer dehydrating chamber or drum advantageously may be in the formof an openended shell 35 of substantially cylindrical or polygonal formsurrounding the intermediate drum 34 and spaced therefrom by supportingmembers The drum or shell 35 is preferably of greater length than theintermediate drum providing an overhanging inlet 45 communicating withthe control chamber C and an overhanging outlet 46 communicating withthe-discharge chamber D which in turn communicates with the outlet 41 bymeans of openings 48. The outlet 4'! advantageously may be acontinuation of the inner drum 33 beyond the end wall 43 which surroundsand is in communication with the discharge outlet ll leading to thecollector [8.

The invention thus provides a series of inner, intermediate and outerdehydrating chambers or zones, which advantageously may be concentricand through which the material flows in a tortuous current. Theprovision of the control chamber C between the intermediate and outerdrying chambers 34 and 35 with the control thermostat therein to varythe volume of products of combustion supplied by the burner 2, makespossible the variation in the temperature in the dehydrator prior to thedischarge of the material affecting the control. It is thus possible, bythe present invention, to correct in the outer dehydrating chamberunsatisfactory dehydrating conditions, as for example by increasing ordecreasing the fuel supply and the volume of prod ucts of combustion,subject to the requirements of an intermediate drying stage, and thusproduce a more uniformly dehydrated product notwithstanding variationsin the moisture content of the raw material fed to the dehydrator.

In addition to varying the heat supplied to the dehydrator it may alsobe desirable to increase or decrease the temperature of dehydratinggases in the outer drying chamber 35 irrespective of the temperature ofthe gases in the inner and intermediate chambers 33 and 34. This may beaccomplished by admitting previously unused hot furnace gases or roomtemperature air directly to the control chamber C for passage solelythrough the drying chamber. This may be accomplished by providing aby-pass 50 from the hot air duct I2 through the casing end 3| and to thecontrol chamber C, and a control damper 5| therein for by-passing aportion of the hot furnace gases directly into the control chamber C.Thus, if the temperature in the outer dehydrating chamber should beincreased, the damper 5: may be opened to by-pass furnace gases directlyto the control chamber around the inner and intermediate chamber.

The by-pass 55] is also provided with a dampercontroiled fresh air inlet54 to admit cooling room temperature air to the chamber C when it isdesired to reduce the temperature in the outer dehydrating chamber.

Additionally, it may be desirable to variably control the rate orfrequency at which the ma terial is tumbled or dropped across thecurrent or dehydrating gases or to vary the velocity of the current ofdehydrating gases or both.

According to the present invention, the rotating dehydrating drums orchambers may be rotated by the rollers 39 driven by the chain andsprocket drive 55 from a driven shaft of a suitable variable speeddrive, diagrammatically illustrated at 56 and subject to the manualcontrol of the operator by lever 55 or the automatic control of thethermostat l I. By increasing or reducing the speed of rotation of thedrums, the frequency of tumbling or dropping the material across thecurrent of dehydrating gases is correspondingly 6 increased or reduced.The larger and heavier particles of material, which are subjected to thetumbling action of the rotating drums, are thus retained in thedehydrating chambers longer as the speed of rotation is reduced and fora lesser period as the speed of rotation is increased.

The more fiocculent and lighter particles of material are supported bythe current of drying gases and the duration of dehydrating treatmentthereof may be variably controlled to suit existing conditions byvarying the velocity of the gas current through the dehydrator.Advantageously, this ma be accomplished by a regulating damper 5'! inthe duct controlled by the fan 20, for example, in the exhaust duct 22.As will be apparent, closing the damper 5'! will reduce the velocity ofthe gas current through the dehydrator, while opening the damper willincrease the velocity thereof.

In practicing the invention, the material to be dehydrated is fed fromthe hopper l4 and chute I3 to the hot air duct I2 in which it isintermixed with the hot furnace gases supplied by the furnace. Thesystem is a substantially closed one by reason of the air lock l5 at thefeeding hopper and the air lock 24 at the sacking machine 25 (except forthe cooling air current between the inner drum 33 and supporting sleeve31 (Figs. 1 to 3)) and hence operation of the suction fan establishes apneumatic current therethrough. This current passes successively throughthe initial stage in the inner drum 33, the intermediate stage in theintermediate drum 34, the final stage in the outer drum 35 and thencethrough discharge outlet l'l, collector I8 and offtake 22, and hassuccessively diminishing velocities in the inner, intermediate and outerdrums b reason of their respective increased cross sectional areas. Thevelocity of the current may be variably contro.led by means of thedamper 57 in the offtake 22.

The material passing through the inner drum is repeatedly lifted by thebuckets or paddles 33 and tumbled or dropped across the pneumaticcurrent of hot gases, and finally is discharged into the intermediatedrum 34 in which it is repeatedly lifted and tumbled or dropped whilebein conveyed therethrough toward the control chamber C.

The material reaching the control chamber is, of course, relativelydehydrated subject to such final dehydration as to produce a finishedproduct of desired moisture content. The thermostat in said controlchamber may be set to maintain a desired temperature therein forentrance into the final or outer dehydrating drum. Optionally, unusedhot gases may be by-passed directly thereto by opening the damper 5| toincrease the temperature of the gases within the final drum whendesired, or cooling air may be admitted thereto by openingdamper-controlled inlet 54 to reduce temperature in the final dryingstage.

Variation of the frequency of tumbling the material in the current aswell as varying the veloc-- ity of the current also aids materially inthe accurate control of dehydration.

The various controls above described, such as the dampers 5|, 54 and 51,as well as the variable speed drive for the dehydrator rotating means,may be manually operated by the operator and such manual operation ispreferred. However, in certain instances it is desirable to operatethese controls automatically and preferably such operation is inresponse to temperature conditions existing in the control chamber 0,

Preferably, the automatic operation of the controls is subject to thethermostat II as illustrated in Fig. 4.

As illustrated in Fig. 4, the thermostat II may be one of the manyconventional types of thermostat, preferably one provided with anadjustment 62 whereby the valve I may be operated at a desiredtemperature.

When the thermostatically controlled valve is opened in response torequirement for additional heat in the control chamber, air or fluidunder pressure may flow from pressure supply line M to the line 6 andbranch lines 6, 6 Ii and 6 The branch line 6 leads to the valve casing 4and provides pressure to lift the valve 5 and admit an additional flowof oil to line 3 leading to the burner 2.

The branch lines 6*, I5 and Ii lead from the line 6 to such othervariable controls as are desired. For example, the lines 6 and 6 maycontrol the dampers 51 and BI, respectively, and for this purpose theincreased pressure in these branch lines may operate motors 63 havingrack and pinion connections with the dampers to rotate them about theirpivotal axes.

Similarly, the line 6 may lead to a pressure operated controlling device'64 connected to the operating lever I54 of the variable speed drivingmechanism 56 of the drum rotating mechanism for shifting the controllever 56 to vary the speed of rotation of the roller drive 39.

The invention may also be embodied in a somewhat difierent constructionof dehydrator in which the outer drum I35 is equipped with tires I38rolling on and driven by supporting and driving rollers I39. In suchdehydrators the outer drum is necessarily imperforate and closed at bothends as shown in Figs. 5 and 6. In such construction the control chamberC between the intermediate and outer drums includes a stationary closureplate I 60, preferably supported on the hot air duct I2, and surroundingthe inlet end I36 of the inner drum I33 and overlying the end flangesI3I of the outer drum I35. The relatively movable surfaces at the jointsbetween the closure I5!) and the drum I35 may be sealed against theinlet of outside air as is usual in the art. This stationary closureplate provides a support for the thermostat I I and one end of theby-pass 50 at the control chamber C.

The end closure I60 conveniently may be supported in position by radialarms I52 on a collar I63 surrounding the hot air duct I2 as shown inFigs. 5 and 6.

The dehydrator shown in Figs. 5 and 6 is designed to be supplied withnatural and hot furnace gases supplied and controlled by means shown inFigs. 1 and 4, and the dried material is removed therefrom as shown inFig. 1.

The invention provides an extremely efficient and economical method forthe dehydration of moisture-laden materials, such for example ascomminuted citrus pulp, shredded forage crops and the like, wherematerials having varying moisture content may be rapidly dehydrated to adesired moisture content.

While the invention has been described with reference to two forms ofapparatus suitable for practicing the method, it is not limited theretobut is intended for illustrative purposes, and I intend that theinvention embody other modifications as defined in the appended claims.

I claim:

1. A dehydrator comprising. concentrically arranged inner, intermediateand outer shells,

means for supplying heated gases to one end of said inner shell, meansfor establishing a pneumatic current of gases successively through saidinner, intermediate and outer shells, said intermediate shell being ofless length than the outer shell providing a control chambertherebetween at one end thereof, temperature responsive means positionedin said control chamber and means for by-passing previously unused gasesfrom said supplying means to said control chamber.

2. A dehydrator unit comprising concentric inner, intermediate and outerdrums, means mounting said drums in spaced-apart relation, said innerdrum having an axial inlet adjacent one end and longitudinally spacedradial openings near the opposite end thereof, a partition between saidlongitudinal spaced openings dividing said inner drum into an initialdehydrating chamber and a discharge chamber, one of said series ofradial openings communicating with the intermediate drum and the otherof said series of radial openings communicating with said outer drum,and an end closure for the intermediate drum disposed in a planeintermediate said longitudinally spaced radial openings.

3. A dehydrator unit comprising concentric inner, intermediate and outerdrums, means mounting said drums in spaced-apart relation, said innerdrum having an axial inlet at one end for intermixed material and hotgases, a tubular member surrounding the inlet end of said inner drum andspaced therefrom, means external of said drums for supporting saidtubular member, means for admitting cooling air to the space between theinner drum and tubular member, means for discharging heated air fromwithin the tubular member to the intermediate drum, and means forrotating said unit through said tubular supporting member.

4. A dehydrator comprising concentric inner, intermediate and outerdrums, means mounting said drums in spaced-apart relation, said innerdrum having an inlet adjacent one end thereof, and an annular chambersurrounding said inlet end of the inner drum and communicating with theintermediate and outer drums, a hot air duct for supplying hot furnacegases to the inlet end of said inner drum, means for establishing apneumatic current of gases successively through said inner drum,intermediate drum, annular chamber and outer drum, and means forby-passing a portion of said gases around said inner drum and into said'chamber for admission into said outer drum.

5. A dehydrator comprising an outer casing and concentric inner,intermediate and outer drums, means mounting said drums in spacedapartrelation, said inner drum having an inlet adjacent one end thereof, anannular chamber surrounding said inlet end of the inner drum andcommunicating with the intermediate and outer drums, means forestablishing a pneumatic current of gases successively through saidinner drum, intermediate drum, annular chamber and outer drum, and anopening in said outer casing for admitting cooling air directly intosaid outer drum.

6. A dehydrator comprising concentrically arranged rotary inner andintermediate drums and an outer drum providing respectively initial,intermediate and final dehydrating zones of progressively increasedduration and extent, means forming a passageway connecting said innerand intermediate drums adjacent one end of the dehydrator, meansincluding a fixed closure forming a passageway connecting saidintermediate and outer drums at an opposite end of said dehydrator,means for supplying heated gases to one end of said inner drum, meansfor establishing a pneumatic current of gases successively through saidinner, intermediate 3 and outer drums, temperature-responsive meansfixedly mounted in the fixed closure and having a portion thereofexposed to the passageway connecting said intermediate and outer drumsfor contact with material-laden gases passing therethrough from saidinner and intermediate drums,

and means actuated by said temperature-responsive means in response tothe drying conditions in said passageway to vary the temperature ofheated gases throughout said initial, intermediate and final dehydratingzones.

'7. A dehydrator comprising concentrically arranged rotary inner andintermediate drums and a fixed outer casing for said drums providingrespectively initial, intermediate and final dehydrating zones ofprogressively increased duration and extent, means forming passagewaysconnecting said inner and intermediate drums at one end and saidintermediate drum and outer casing at an opposite end, means forsupplying heated gases and material to be dried to one end of said innerdrum, means for establishing a pneumatic current of gases successivelythrough said inner and intermediate drums and said outer casing,temperature-responsive means fixedly mounted in the outer casing andhaving a portion thereof exposed to the passageway connecting saidintermediate and outer drums for contact with material-laden gasespassing therethrough from said inner and intermediate drums, and meansactuated by said temperature-responsive means in response to the dryingconditions in said passageway to vary the temperature of heated gasesthroughout said initial, intermediate and final dehydrating zones.

8. A dehydrator comprising concentrically arranged rotary inner andintermediate drums and an outer drum providing respectively initial,intermediate and final dehydrating zones of progressively increasedduration and extent, a fixed closure for said outer drumv means forminga passageway connecting said inner and intermediate drums adjacent oneend of the dehydrator, means including said fixed closure forming apassageway connecting said intermediate and outer drums at an oppositeend of said dehydrator, means for supplying heated gases to one end ofsaid inner drum, means for establishing a pneumatic current of gasessuccessively through said inner, iiitermediate and outer drums,temperature-responsive means fixedly mounted in the fixed closure andhaving a portion thereof exposed to passageway connecting saidintermediate and outer drums for contact with material-laden gasespassing therethrough from said inner and intermediate drums, and meansactuated by said temperature-responsive means in response to the dryingconditions in said passageway to vary the temperature of heated asesthroughout said initial, intermediate and final dehydrating zones.

9. A dehydrator comprising concentrically arran ed rotary inner andintermediat d um a d fixed outer drum provi ing r sp c ively initiel,intermediate and final dehydrating zones of progressively increasedduration and extent, means forming a pa sageway connecting said innerand intermediate drums adjacent one end of the dehydrator, meansincluding a fixed closure forming a passageway connecting saidintermediate and outer drums at an opposite end of said dehydrator,means for supplying heated gases to one end of said inner drum, meansfor establishing a pneumatic current of gases successively through saidinner, intermediate and outer drums, temperature-responsive meansfixedly mounted in the fixed closure and having a portion thereofexposed to the passageway connecting said intermediate and outer drumsfor contact with material-laden gases passing therethrough from saidinner and intermediate drums, and means actuated by saidtemperature-responsive means in response to the drying conditions insaid passageway to vary the velocity of heated gases throughout saidinitial, intermediate and final dehydrat 'ing zones.

10. A dehydrator comprising concentrically arranged rotary inner andintermediate drums and a fixed outer drum providing respectivelyinitial, intermediate and final dehydrating zones of progressivelyincreased duration and extent, means forming a passageway connectingsaid inner and intermediate drums adjacent one end of the dehydrator,means including a fixed closure forming a passageway connecting saidintermediate and outer drums at an opposite end of said dehydrator,means for supplying heated gases 'to one end of said inner drum, meansfor establishing a pneumatic current of gases successively through saidinner, intermediate and outer drums, said rotary drums having internalmaterial-lifting means for lifting and dropping material across saidcurrent, temperature-responsive means fixedly mounted in the fixedclosure and having a portion thereof exposed to the passagewayconnecting said intermediate and outer drums for contact withmaterial-laden gases passing therethrough from said inner andintermediate drums, and means actuated by said temperature-responsivemeans in response to the drying conditions in said passageway to varythe rate of lifting and dropping material across said current throughoutsaid initial, intermediate and final dehydrating zones.

11. A dehydrator comprising concentrically arranged rotary inner andintermediate drums and a fixed outer drum providing respectivelyinitial, intermediate and final dehydrating zones of progressivelyincreased duration and extent, means forming a passageway connecting sad inner and intermediate drums adjacent one end of the dehydrator, meansincluding a fixed closure forming a passageway connecting saidintermediate and outer drums at an opposite end of said dehydrator,means for supplying heated gases to one end of said inner drum, meansfor establishing a pneumatic current of gases successively through saidinner, intermediate and outer drums, said rotary drums having internalmaterial-lifting means for lifting and dropping material across saidcurrent, temperature-responsive means fixedly mounted in the fixedclosure and having a portion thereof exposed to the passagewayconnecting said intermediate and outer drums for contact withmaterial-laden gases passing therethrough from said inner andintermediate drums, and means actuated by said temperature-responsivemeans in response to the drying conditions in said passageway to varythe rate of lifting and dropping material across said current and thetemperature and velocity of heated gases throughout said initial.intermediate and final dehydrating zones.

12. A dehydrator unit comprising concentric inner, intermediate andouter drums, means mounting said drums in spaced-apart relation,

said inner drum having an axial inlet adjacent one end and a pluralityof series of longitudinally spaced radial openings near the opposite endthereof, a partition in said inner drum positioned intermediate theadjacent ends of said series of spaced openings and dividing said innerdrum into an initial dehydrating chamber communieating with saidintermediate drum through one series of openings and a discharge chambercommunicating with said outer drum through another series of openings.

13. A dehydrator unit comprising concentric inner, intermediate andouter drums, means mounting said drums in spaced-apart relation, saidinner drum having an axial inlet at one end for intermixed material andhot gases, a tubular member surrounding the inlet end of said inner drumand spaced therefrom to form an annular chamber, said tubular memberextending within the intermediate drum and having openings at both ends,and means for supporting and rotating said inner and intermediate drums.

14. A dehydrator unit comprising concentric rotary inner andintermediate drums and a fixed outer drum, means mounting said drums inspaced-apart relation, said inner drum having an axial inlet at one endfor intermixed material and hot gases, a tubular member surrounding theinlet end of said inner drum and spaced therefrom to form an annularchamber, said tubular member extending within the intermediate drum andhaving openings at both ends, an annular tire on one end of the tubularmember, and a roller drive engaging said tire for supporting androtating said rotary drums.

15. A dehydrator unit comprising concentric rotary inner andintermediate drums and a fixed outer drum, means mounting said drums inspaced-apart relation, said inner drum having an axial inlet at one endfor intermixed material and hot gases, a tubular member surrounding theinlet end of said inner drum and spaced therefrom to form an annularchamber, said tubular member extending within the intermediate drum andbeing fixed to the inner drum, means for introducing a current of airinto the tubular member for insulating it against the heat of the inletend of the inner drum, and means supporting and rotating said rotarydrums through said tubular member.

16. A dehydrator unit comprising concentric rotary inner andintermediate drums and a fixed outer drum, means mounting said drums inspaced-apart relation, said inner drum having an axial inlet at one endfor intermixed material and hot gases, a tubular member surrounding theinlet end of said inner drum and spaced therefrom to form an annularchamber, said tubular member extending within the intermediate drum,means for establishing a current of air through said annular chamberbetween said inner drum and tubular member, and means supporting androtating said rotary drums through said tubular member.

DANIEL B. VINCENT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 703,508 Ward July 1, 1902 742,265Wentz Oct. 27, 1903 862,225 Westphal Aug. 6, 1907 1,175,944 Ford et a]Mar. 21, 1916 1,229,524 Rosendahl June 12, 1917 1,326,525 Nordstrom etal Dec. 30, 1919 1,336,422 Burman Apr. 13, 1920 1,988,677 Arnold Jan.22, 1935 2,038,008 Shodron Apr. 21, 1936 2,132,656 Smith Oct. 11, 19382,143,505 Arnold Jan. 10, 19 9 2,173,225 Berry et a1. Sept. 19, 19392,226,910 Rice Dec. 31, 1940 2,316,459 Schmidt et a1 Apr. 13, 19432,319,673 French May 18, 1943 2,341,101 Howard Feb. 8, 1944 2,409,787ONeal Oct. 22, 1946 FOREIGN PATENTS Number Country Date 490,373 GreatBritain Aug. 12, 1938 Certificate of Correction Patent No. 2,518,582 LAugust 15, 1950 DANIEL B. VINCENT It is hereby certified that errorappears in the printed specification of the above numbered patentrequiring correct1on as follows:

Column 5, line 63, for the word or, first occurrence, read of; column 8,line 46, for the indistinct Word after air read duct; column 9, line 58,after to insert the;

and that the said Letters Patent should be read as corrected above, sothat the same may conform to the record of the case in the PatentOffice.

Signed and sealed this 14th day of November, A. D. 1950.

[SEAL] THOMAS F. MURPHY,

Assistant Commissioner of Patents.

